/*
 * Copyright (C) 2013, 2014 Brett Wooldridge
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.zaxxer.hikari.pool;

import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A Runnable that is scheduled in the future to report leaks. The
 * ScheduledFuture is cancelled if the connection is closed before the leak time
 * expires.
 *
 * @author Brett Wooldridge
 */
class ProxyLeakTask implements Runnable {
	private static final Logger LOGGER = LoggerFactory.getLogger(ProxyLeakTask.class);
	static final ProxyLeakTask NO_LEAK;

	private ScheduledFuture<?> scheduledFuture;
	private String connectionName;
	private Exception exception;
	private String threadName;
	private boolean isLeaked;

	static {
		NO_LEAK = new ProxyLeakTask() {
			@Override
			void schedule(ScheduledExecutorService executorService, long leakDetectionThreshold) {
			}

			@Override
			public void run() {
			}

			@Override
			public void cancel() {
			}
		};
	}

	ProxyLeakTask(final PoolEntry poolEntry) {
		this.exception = new Exception("Apparent connection leak detected");
		this.threadName = Thread.currentThread().getName();
		this.connectionName = poolEntry.connection.toString();
	}

	private ProxyLeakTask() {
	}

	void schedule(ScheduledExecutorService executorService, long leakDetectionThreshold) {
		scheduledFuture = executorService.schedule(this, leakDetectionThreshold, TimeUnit.MILLISECONDS);
	}

	/** {@inheritDoc} */
	@Override
	public void run() {
		isLeaked = true;

		final StackTraceElement[] stackTrace = exception.getStackTrace();
		final StackTraceElement[] trace = new StackTraceElement[stackTrace.length - 5];
		System.arraycopy(stackTrace, 5, trace, 0, trace.length);

		exception.setStackTrace(trace);
		LOGGER.warn("Connection leak detection triggered for {} on thread {}, stack trace follows", connectionName, threadName, exception);
	}

	void cancel() {
		scheduledFuture.cancel(false);
		if (isLeaked) {
			LOGGER.info("Previously reported leaked connection {} on thread {} was returned to the pool (unleaked)", connectionName, threadName);
		}
	}
}
